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Dermatomiositis is one of the idiopathic inflammatory myopathies in which characteristic cutaneous disease is present. A related condition known as polymyositis appears to be similar in its muscle pathology, differing only in its lack of skin findings. Recently, another myopathy, known as inclusion body myositis, has been described. Skin findings are rare in this subset of idiopathic inflammatory myopathies. Polymyositis, and less commonly dermatomyositis, may occur in conjunction with other rheumatic diseases such as systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis (i.e., overlap connective tissue disease). Dermatomyositis, and less commonly polymyositis, may occur as a

The idiopathic inflammatory myopathies are systemic autoimmune disorders that are expressed predominantly in the skin and proximal skeletal musculature. However, other organs such as the lung and heart may be involved. A systemic vasculopathy, which can produce disease in other organs such as the gastrointestinal tract, is frequently present in children with dermatomyositis. In some patients, the florid cutaneous manifestations of dermatomyositis may be present for many years in the absence of clinical and enzymatic evidence of muscle disease (i.e., amyopathic dermatomyositis or dermatomiositis sine myositis).

Dermatomyositis/polymyositis is one of the least common of the rheumatic diseases, occurring in approximately 5 in each million persons. The female/male ratio for dermatomyositis is Approximately 10% of patients with dermatomyositis have their disease expressed as amyopathic dermatomyositis.

Untreated polymyositis can produce severe and long-term disabilities from muscle atrophy and weakness. The active cutaneous manifestations of dermatomyositis can produce great discomfort from intractable pruritus, which in some patients may be completely disabling. The

Diagnostic criteria


History may include

Progressive, symmetric weakness accentuated in proximal muscle groups

Use of drugs (e.g., clofibrate, ipecac, corticosteroids, and

Physical examination may include

The diagnosis of dermatomyositis is confirmed by the presence of diagnostic skin lesions (items 1 and 2 below) or by characteristic

Associated conditions


Pulmonary fibrosis

Cardiac disease


Dysphagia, dysphonia


A diagnosis of dermatomyositis can be made in a patient with biopsy-confirmed classic skin findings, proximal muscle weakness, and elevated muscle enzymes (creatine kinase, aldolase). The diagnosis can be strengthened by confirming that the muscle weakness is due to active myositis through diagnostic changes demonstrated by electromyography and/or muscle biopsy.

Skin biopsy

The histopathologic features seen in the skin lesions of dermatomyositis are not specific for dermatomyositis because very similar changes can also be seen in acute lupus erythematosus (dermal mucinosis is relatively more prominent in dermatomyositis


Dosage recommendations in this document are for an


Each patient's management depends on the severity of the skin and muscle disease, the presence or absence of malignancy, and the


Both cutaneous as well as muscle disease may be exacerbated by sunlight.

Adequate nutrition

Good nutrition, including adequate dietary intake of

A large percentage of patients with dermatomyositis will require some form of therapy for their pruritic skin discomfort, which can

Topical corticosteroids usually in an ointment base are occasionally helpful, but care should be taken to

Aminoquinoline antimalarials

Oral hydroxychloroquine, 200 to 400 mg/day, can aid in the control of the skin disease in

Systemic corticosteroids (oral)

Prednisone, 0.5 to 1.5 mg/kg per day, can be of

Muscle disease

Systemic corticosteroids

Systemic corticosteroids are used in doses sufficient to These agents include, but are not limited to

Oral or intravenous methotrexate

Oral azathioprine

Oral cyclophosphamide or intermittent intravenous pulsed cyclophosphamide

Oral chlorambucil

Oral cyclosporine


Surgical removal of medically unresponsive, symptomatic calcium deposits is


Skin disease

Low-dose methotrexate, azathioprine, and cyclosporine for control of cutaneous inflammatory disease

Diphosphonates, aluminum hydroxide, probenecid, colchicine, and low-dose warfarin to treat the cutaneous calcinosis that can be seen in dermatomyositis (especially in children); however,

Muscle disease

Intravenous immunoglobulin

Total body irradiation

Plasmapheresis (Recent controlled data have